Dangerous Times for Right Whales
It’s been a terrible year for right whales (Eubalaena glacialis). There have been sixteen deaths so far in 2017. With a total population of fewer than 500 right whales, sixteen fatalities is way too many. Why are right whale numbers so low, and what are the biggest threats to their survival?
The right whale population was decimated centuries ago by hunting. They were considered the “right” whales to hunt. Right whales were relatively easy to kill because they swim slowly and close to shore. They also float when dead because of their high blubber. Their large (up to 60’) bodies yielded valuable blubber that was used for oil to light lamps. Baleen, used by whales to filter the zooplankton they eat from seawater, was used by people to whip horses and cinch in wastes. Right whales were so heavily hunted that by the 1750’s, commercial hunting was no longer profitable. Whale hunting was banned worldwide in 1949.
Right whales migrate to the coastal waters off Nova Scotia and New England to feed, and then pregnant females travel south to the waters off Georgia and Florida in winter to give birth. This puts them in some of the busiest shipping lanes in the world. Ship collisions have taken a big toll on this slow-moving whale. In an effort to save the whale, the National Oceanic and Atmospheric Administration regulated ship speed in 2009. Ships over 65’ can travel no faster than ten knots in certain areas at certain times of the year when right whales are likely to be present. There are additional voluntary speed restrictions in areas where right whales are sighted. These restrictions are helping, and the number of collisions has fallen in slow-speed zones.
While death by ship has decreased, mortality through entanglement is increasing. Entanglement in fishing gear is the number one threat to right whales today. Eighty-three percent of all right whales bear scars from ropes. Many have scars from multiple entanglements. Fishing gear entanglement often has grave health consequences even when it doesn’t cause dismemberment or death. Entanglement may be the reason right whales are not reproducing as often or living as long as they have in the past.
Vertical ropes, like those attached to crab pots, lobster traps or gill nets used for bottom fish, are especially dangerous. Closing fisheries during right whale season, reducing the number of vertical lines in the water and promoting the use of sinking ground line are all being considered to reduce the risks to whales.
The National Marine Fisheries Service has a warehouse full of ropes removed from whales as well as data on every entanglement. In a promising new study, researchers analyzed this fishing gear and data and found that reducing the breaking strength of the rope could reduce probability of death. Fishing gear was originally made from weaker, biodegradable natural fibers, but these were replaced with synthetic material in the 1950’s. Blends of different plastics came on the market in the mid-1990’s, and these are widely used today. These new lines do not biodegrade, and they are very strong. Most are much stronger than they need to be for the job they do. Young whales and weaker species of whales, like minke, are less likely to break free from stronger ropes. Researchers determined that reducing the breaking strength of ropes to 1700 pounds could cut the probability of death by 72%.
Right whales need a less perilous ocean fast. A baby boom would really help too. Pregnant whales are heading south to Georgia and Florida now, and should start giving birth soon. Let’s hope it’s a bumper year for baby right whales and that 2018 is less treacherous for them too.